During the next five years of my studies will be directed towards understanding the distribution of coronary microvascular resistance in animals with hypertension and left ventricular hypertrophy (HT- LVH). These studies evaluate the effects of hypertension and left ventricular hypertrophy on: the distribution of coronary microvascular resistance, the microvascular site for autoregulation, the effects of adenosine vasodilatation, characteristics of microvascular permeability, quantitation of microvascular permeability and the microvascular responses to acute myocardial ischemia. To evaluate these mechanisms we have developed a system whereby left ventricular microvascular pressures, diameters and a direct evaluation of permeability are performed in epicardial microvessels of the freely beating left ventricle in both normal animals and animals with hypertension and left ventricular hypertrophy.